CODEWITHSUNDEEP
c#linqlinq-to-sqllambda
mark smith
mark smith

Reputation: 20907

LINQ: Help with linq query and contains for an IEnumerable<string>?

Can anyone help?

I have a linq query which is embedded inside a extension method, it was working as v.RentalStatus was a String. I am now using a Group on my original query (the query is quite complex so i won't put it here).

The importante thing is that v.RentalStatus = IEnumerable hence it can contain things like

A (meaning active)
R (meaning rented)
U (unavailable)

etc - many more

I create a list of what i would like to get back and store this in statusStringList, so for example lets say the list contains A and R

This is my code from before when the v.RentalStatus was just a string, can anyone tell me how i can modify this to work.

        var statusStringList = rentalStatus.ToList().ConvertAll<string>(st => st.GetStringValue());

        return from v in qry
               where statusStringList.Contains(v.RentalStatus)
               select v;

If it helps this is part of my query which returns the RentalStatus - its part of a group query but the RentalStatus is not in the group by

 RentalStatus= g1.Select( j => j.IdRentalStatus).Distinct(),

g1 is my group by, so if you imagine there are 10 "A", 5 "U" .. then it would return an ienumerable of A and U ... as i am using Distinct. Not 10 As and 5 Us

I hope i have explained it well, please tell me if i haven't

I would appreciate any help from anyone ..

thanks

EDIT

This is my extension signature but not that it matters.

    public static IQueryable<Rentals> WithStatus(this IQueryable<Rentals> qry, IList<Contants.Statuses> rentalStatus)
    {

EDIT

As mentioned previously when v.RentalStatus was a string it was working but now its IEnumerable - hence a collection.. and it errors with this

  Argument '1': cannot convert from 'System.Collections.Generic.IEnumerable<string>' to 'string'

Upvotes: 1

Views: 12613

Answers (4)

bytebender
bytebender

Reputation: 7491

If RentalStatus has changed from a string to a IEnumerable<string> then your comparing 2 list... I think this should work:

return from v in qry
    where v.RentalStatus.Any(status => statusStringList.Contains(status))
    select v;

This should give you any rentals that have a status that is in the list you are providing

Edit:

Yeah I would spend some time learn lambda expressions. Seems like they are being used more and more and with good reason. Here are a few links for tutorials:

An Extensive Examination of LINQ: Lambda Expressions and Anonymous Types

.NET Lambda Expressions – Resources

"WHERE" RentalStatus = Containing any of itself - arrgghh -

Is that true? I thought the list of rentalStatuses is a parameter in your method. I was thinking your query basically would allow me to get all the rentals that have a status that matches any of the list that I specified. One list lives on your Rental object and the other is the one I pass in...

As to why the order in mine worked. I have some questions:

Are you using this to query a database? Are you able to look at the tsql it generates?

If so, I would look at the tsql and see what the difference is. I would have to check myself. I got lucky I guess.

Upvotes: 3

Gabe Moothart
Gabe Moothart

Reputation: 32082

Try this:

    return from v in qry
           where rentalStatus.Any( r => r.IdRentalStatus == v.RentalStatus)
           select v;

Upvotes: 0

John Fisher
John Fisher

Reputation: 22719

You could try something like this:

where statusStringList.Any(x => v.RentalStatus.Contains(x))

Upvotes: 1

Marcel Gosselin
Marcel Gosselin

Reputation: 4716

I am not sure but I think that for a Contains to work in Linq to SQL it must be an array of strings (or ints or ...) and not any IEnumerable. I would thus try:

var statusStringArray = rentalStatus.ToList().ConvertAll<string>(st => st.GetStringValue()).ToArray();

return from v in qry
       where statusStringArray.Contains(v.RentalStatus)
       select v;

There might be other issues though, I did not look that much.

Upvotes: 0

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